The inverted eye—example of bad design?

Kenneth Miller, the Roman Catholic evolutionist who is featured prominently on PBS 1, claims that the eye has ‘profound optical imperfections,’ so is proof of ‘tinkering’ and ‘blind’ natural selection. Miller hasn’t presented an argument for evolution per se at all—because he presents no step-by-step way for the retina to have evolved—but it is purely an attack on a Designer. Which is, of course, also an attack on Miller’s own Darwinian version of ‘god,’ one who has chosen to create indirectly (via evolution).

Miller raised the old canard of the backwardly wired vertebrate retina, as he has done elsewhere. The narrator even claimed that the eye’s ‘nerves interfere with images,’ and that the so-called ‘blind spot’ is a serious problem. But these arguments have been refuted before, as shown below.

It would be nice if anti-creationists actually learned something about the eye before making such claims (Miller is unqualified in both physical optics and eye anatomy), or even showed that the eye didn’t function properly as a result. In fact, any engineer who designed something remotely as good as the eye would probably win a Nobel Prize! If Miller and the PBS producers disagree, then I challenge them to design a better eye with all the versatility of the vertebrate eye (color perception, resolution, coping with range of light intensity, night vision as well as day vision, etc.)! And this must be done under the constraints of embryonic development.

The retina can detect a single photon of light, and it’s impossible to improve on this sensitivity! More than that, it has a dynamic range of 10 billion (1010) to one; that is, it will still work well in an intensity of 10 billion photons. Modern photographic film has a dynamic range of only 1,000 to one. Even specialist equipment hasn’t anywhere near the dynamic range of the eye, and I have considerable experience in state-of-the-art supersensitive photomultipliers. My Ph.D. thesis and published papers in secular journals largely involve a technique called Raman spectroscopy, which analyzes extremely weak scattering at a slightly different frequency from that of the incident laser radiation. The major equipment hazard for Raman spectroscopists is scanning at the incident frequency—the still weak Rayleigh scattering at the same frequency would blow the photomultiplier (the newer ones have an automatic shut-off). I managed to safely scan the Rayleigh line (for calibration) only by using filters to attenuate the intensity of light entering the photomultiplier by a factor of 10-7 to 10-8. But having to take such an extreme safety precaution made me envious and admiring of the way the eye is so brilliantly designed to cope with a far wider range of intensities.

Another amazing design feature of the retina is the signal processing that occurs even before the information is transmitted to the brain, in the retinal layers between the ganglion cells and the photoreceptors. For example, a process called edge extraction enhances the recognition of edges of objects. Dr John Stevens, an associate professor of physiology and biomedical engineering, pointed out that it would take ‘a minimum of a hundred years of Cray [supercomputer] time to simulate what takes place in your eye many times each second.’1 And the retina’s analog computing needs far less power than the digital supercomputers and is elegant in its simplicity. Once again, the eye outstrips any human technology, this time in another area.

Someone who does know about eye design is the ophthalmologist Dr George Marshall, who said:

The idea that the eye is wired backward comes from a lack of knowledge of eye function and anatomy.

He explained that the nerves could not go behind the eye, because that space is reserved for the choroid, which provides the rich blood supply needed for the very metabolically active retinal pigment epithelium (RPE). This is necessary to regenerate the photoreceptors, and to absorb excess heat. So it is necessary for the nerves to go in front instead. The claim on the program that they interfere with the image is blatantly false, because the nerves are virtually transparent because of their small size and also having about the same refractive index as the surrounding vitreous humor. In fact, what limits the eye’s resolution is the diffraction of light waves at the pupil (proportional to the wavelength and inversely proportional to the pupil’s size), so alleged improvements of the retina would make no difference.

It’s important to note that the ‘superior’ design of Miller with the (virtually transparent) nerves behind the photoreceptors would require either:

The choroid in front of the retina—but the choroid is opaque because of all the red blood cells, so this design would be as useless as an eye with a hemorrhage!

Photoreceptors not in contact with the RPE and choroid at all—but the photoreceptors would be slow to regenerate, so it would probably take months before we could drive after we were photographed with a flashbulb.

Some evolutionists claim that the cephalopod eye is somehow ‘right,’ i.e., with nerves behind the receptor, and the program showed photographs of these creatures (e.g., octopus, squid) during this segment. But no one who has actually bothered to study these eyes could make such claims with integrity. In fact, cephalopods don’t see as well as humans, and the octopus eye structure is totally different and much simpler. It’s more like ‘a compound eye with a single lens.’

Ophthalmologist Peter Gurney gives a detailed response to the question ‘Is the inverted retina really “bad design”?’2 He addresses the claim that the blind spot is bad design, by pointing out that the blind spot occupies only 0.25% of the visual field, and is far (15°) from the visual axis so that the visual acuity of the region is only about 15% of the foveola, the most sensitive area of the retina right on the visual axis. So the alleged defect is only theoretical, not practical. The blind spot is not considered handicap enough to stop a one-eyed person from driving a private motor vehicle. The main problem with only one eye is the lack of stereoscopic vision.

The program also alleges that the retina is badly designed because it can detach and cause blindness. But this doesn’t happen with the vast majority of people, indicating that the design is pretty good. In fact, retinal detachment is more due to the vitreous (‘glassy’) humor liquefying from its normally fairly rigid gel state with advancing age. Then the remaining gel pulls away from the retina, leaving tiny holes, so the other liquefied humor can lift off the retina. So one recently devised treatment is draining the liquid and injecting magnetized silicone gel, which can be moved into place with a magnetic field, to push the retina back and block the holes.3 The occasional failures in the eye with increasing age reflect the fact that we live in a fallen world—so what we observe today may have deteriorated from the original physically perfect state, where, for example, deterioration with age didn’t occur.

To answer other alleged ‘bad design’ arguments, there are two principles to consider:

Do we have all the information/knowledge on the issue?

Could this particular biological system have gone downhill since the Fall?

Panda’s ‘thumb’

Evolutionists have long cited the panda’s clumsy-looking ‘thumb’ as evidence of evolution, rather than intelligent design. Gould even wrote a book called The Panda’s Thumb: More Reflections in Natural History (1980) which says that the panda’s thumb ‘wins no prize in an engineer’s derby.’4

On closer inspection, however, there is nothing clumsy at all about the panda’s design.5 Instead, the ‘thumb’ is part of an elaborate and efficient grasping structure that enables the panda to strip leaves from bamboo shoots.6

Claims that the panda’s thumb is some kind of nondesigned ‘contraption’ is a smokescreen to distract from the real question—that evolution simply does not explain how life could start in a pond and finish with a panda.

‘Junk’ DNA

Each time that evolutionists discover new sections of DNA that have no known function, they like to describe it as ‘junk’ DNA that is a leftover of evolution. For example, the DNA of organisms more complex than bacteria contains regions called exons that code for proteins, and non-coding regions called introns. So the introns are removed and the exons are ‘spliced’ together to form the mRNA (messenger RNA) that is finally decoded to form the protein. This also requires elaborate machinery called a spliceosome. This assembles on the intron, chops it out at the right place, and joins the exons together. This must be in the right direction and place, because it makes a huge difference if the exon is joined even one letter off.

But it’s absurd even on the face of it that more complex organisms should evolve such elaborate machinery to splice the introns if they were really useless. Rather, natural selection would favor organisms that did not have to waste resources processing a genome filled with 98 percent of junk. And there have been many uses for junk DNA discovered, such as the overall genome structure and regulation of genes, and to enable rapid post-Flood diversification.7 Also, damage to introns can be disastrous—one example was deleting four ‘letters’ in the center of an intron, preventing the spliceosome from binding to it, resulting in the intron being included.8 Mutations in introns interfere with imprinting, the process by which only certain maternal or paternal genes are expressed, not both. Expression of both genes results in a variety of diseases and cancers.9

Dr John Mattick of the University of Queensland in Brisbane, Australia, has published a number of papers arguing that the non-coding DNA regions, or rather their non-coding RNA ‘negatives,’ are important for a complicated genetic network.10 These interact with each other, the DNA, mRNA, and the proteins. Mattick proposes that the introns function as nodes, linking points in a network. The introns provide many extra connections, to enable what in computer terminology would be called multi-tasking and parallel processing.

In the case of life, this could control the order in which genes are switched on and off. This means that a tremendous variety of multicellular life could be produced by rewiring the network. In contrast, ‘early computers were like simple organisms, very cleverly designed, but programmed for one task at a time.’11 The older computers were very inflexible, requiring a complete redesign of the network to change anything. Likewise, single-celled organisms such as bacteria can also afford to be inflexible, because they don’t have to develop from embryos as multi-celled creatures do.

Mattick suggests that this new system somehow evolved (despite the irreducible complexity) and in turn enabled the evolution of many complex living things from simple organisms. The same evidence is better interpreted from a biblical framework—indeed this system can enable multicellular organisms to develop from a ‘simple’ cell—but this is the fertilized egg. This makes more sense, since the fertilized egg has all the programming in place for all the information for a complex life form to develop from an embryo. It is also an example of good design economy pointing to a single Designer as opposed to many. In contrast, the first simple cell to evolve the complex splicing machinery would have no information to splice.

But Mattick may be partly right about diversification of life. Creationists also believe that life diversified—after the Flood. However, this diversification involved no new information. Some creationists have proposed that certain parts of currently non-coding DNA could have enabled faster diversification,12 and Mattick’s theory could provide still another mechanism.

Evolutionists have produced a long list of examples of ‘bad design,’ but nothing on the list stands up under scrutiny.

Note about citations: Quotations from the Scientific American article by John Rennie will be labeled ‘SA,’ followed by the page number. Quotations from, and other mentions of, the PBS-TV series ‘Evolution,’ will be labeled ‘PBS,’ followed by the episode number, e.g. ‘PBS 6’ refers to Episode 6. Return to article.
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